Imagers, particularly CMOS imagers, in the past have had problems with scenes that have a high dynamic range such that parts of the scene have highlights therein. This is termed scene exposure latitude. In these highlighted portions of the image, the pixels of the sensor become saturated, such that the digital pixel outputs are all 1's. Accordingly, the pixels of the sensor are especially saturated when the captured scene contains more dynamic range than typically can be captured; for example, a couple standing in the park with the sun over their shoulder. The normal scene can have a dynamic range of 6 to 7 stops. The image of the sun introduces another 10 stops of dynamic range. Current state of the art cameras set the exposure level to capture the couple and allow the sun to saturate the image in the resultant picture. Similar circumstances exist with images that contain specular reflections, for example, the sun reflecting off a metallic car bumper. One other exemplary troublesome scene to capture contains a car in a parking lot, at night. To expose the car correctly, the car headlights and the streetlights illuminating the parking lot will ultimately saturate the image. Consequently, for conventional imaging systems, very little error in determining exposure can be tolerated when the scene dynamic range is close to, or equal to the dynamic range of the image capture system.
What is needed is an image capture system that always has a dynamic range greater than the captured scene.